This invention relates to generally an electrostatic copying machine, and more particularly to a developer transportation device for promptly uniformly supplying developer to a developing roller.
In recent years, an electrostatic copying machine has been developed comprising a longitudinally oriented transportation device and a developer supply container positioned at one side end of the developer transportation device. Such a developer transportation device has been widely used in the electrostatic copying field. Having the supply container at one side end of the developer transportation device permits the container to be easily accessible for replenishing developer. As a result, it is unnecessary to remove the developer transportation device from the main body of the copying machine when refilling the container. Rather, the supply container alone can be removed by pulling it out from engagement with the main body.
A developer transportation device having such a structure is shown in U.S. Pat. No. 3,764,208 (Takahasi et al). The developer transportation means disclosed in this patent (see FIG. 12) comprises a pair of parallel screw rollers adapted for moving the developer in diverse directions to provide a uniform level of developer within the body of the transportation means. In addition to utilizing a pair of rollers, further structure is required for moving the developer in diverse directions. In particular, a plurality of gears are employed for turning one roller in a first angular direction while turning the other roller in a second angular direction opposite to the first angular direction. Consequently, this prior art developer transportation device has the disadvantage of requiring many additional elements for its operation and, thereby, producing a complicated structure for transporting the developer.